Comparison of Relative Activation Energies Obtained by Density Functional Theory and the Random Phase Approximation...

Area of Science:

• Computational Chemistry
• Quantum Chemistry
• Theoretical Chemistry

Background:

• Accurate calculation of reaction energies is crucial in chemistry.
• Density functional theory (DFT) offers various approaches for these calculations.
• Pericyclic reactions provide a valuable test case for evaluating theoretical methods.

Purpose of the Study:

• To compare the performance of different DFT functionals for pericyclic reactions.
• To assess the accuracy of relative activation and free energies.
• To evaluate the treatment of steric and weak interactions by various computational methods.

Main Methods:

• Investigated standard hybrid (B3LYP), augmented hybrid, meta-hybrid (M06-2X), and random phase approximation (RPA) DFT methods.
• Calculated relative activation energies and estimated free energies for model pericyclic reactions.
• Included the amide acetal Claisen rearrangement as a specific case study.

Main Results:

• All tested DFT methods showed similar trends in relative reactivity.
• The random phase approximation (RPA) provided results closest to experimental values.
• Comparison focused on relative activation energies to analyze steric and weak interaction effects.

Conclusions:

• DFT methods provide comparable reactivity trends for pericyclic reactions.
• The RPA method demonstrates superior accuracy for predicting experimental activation energies.
• The chosen set of reactions serves as an effective benchmark for assessing weak interaction treatments in DFT.